Various types of automatic, body-implantable medical devices such as cardiac pacemakers, cardiac defibrillators, cardioverters, neural stimulators and the like, have been shown in the prior art. The majority of these products offer a full range of diagnostic routines that can be selected by the physician or medical technician. As the diagnostic capabilities of the devices increase the selection process by the physician or technician becomes that much more complicated. Upon implantation, or at any other point when the device is being accessed, the doctor must try to look into the future to determine what may happen so that he or she may determine what diagnostic routines to select. The underlying problem is that devices today have far more ability to capture diagnostic data than they have the memory capacity to store.
Because of the lack of memory, physicians and technicians are forced to select which parameters to track. If the physician has chosen to track the frequency and extent of ventricular tachycardia, then atrial undersensing due to a lead that is rapidly failing may not be detected. What is needed is an implantable device that is capable of selecting at any given time what is most important to track. The device should further be capable of allocating the limited memory available within the device for storage of the most important data collected since the last interface with the device.